Design and test of an improved crashworthiness small composite airframe

Original publisher: Hampton, Va. : National Aeronautics and Space Administration, Langley Research Center ; [Springfield, Va. : For sale by the National Technical Information Service, 2002] OCLC Number: (OCoLC)60338737 Excerpt: ... hydraulic actuator. Cam follower beadngs were used to minimize friction. The complete rig with a model installed is shown in Figure 2 ( b ). The first two test attempts on a hard surface showed that the model would chip the concrete floor or gouge a steel plate if the model tried to slide on the surface. The method devised to eliminate this problem was to have the model contact a steel plate riding on another steel plate with axle grease between the plates to minimize friction. Since there was no relative motion between the mount and the top plate, there was no damage to the contact surface using this procedure. Nearly one quarter of the mass of the airplane is in the installed propulsion system with most of that mass mounted on the engine mount. This has the effect of putting a concentrated load on the engine mount until the propulsion system is brought to rest and it was thought this should be simulated in the test. An extension to the carriage was made which allowed an auxiliary actuator to be placed between this extension and the model. A load could be placed on this actuator during the early portion of the stroke until it was judged that the propulsion system kinetic energy would be dissipated. During the first hard surface test, it was realized that this load was simply pushing through the stiffest portion of the mount to the floor which meant that the engine would also do the same thing and be brought to rest very quickly. Later discussion of the full scale hard surface tests will show that this did in fact happen. Use of the auxiliary actuator was discontinued for the hard surface tests but it was used for the soft soil tests where it was thought to still be appropriate. 4.1.2 Instrumentation Instrumentation consisted of loa...